A very long thread on Microsoft's support site dedicated to Windows 7 battery problems started in June 2009, and remains active.

Users are complaining of battery issues, including premature warnings that the power is exhausted, as well as more dire demands to replace the battery.

Microsoft said that that the problem was in the Windows 7 tool that decided when the battery had been drained, or was unable to hold a charge. "We are investigating this issue in conjunction with our hardware partners, which appears to be related to system firmware (BIOS)," a Microsoft spokeswoman said today. "The warning received in Windows 7 uses firmware information to determine if battery replacement is needed."